Modern dentistry has spawned a wide variety of hand-held instruments specifically tailored for manual procedures commonly performed by a dentist or hygienist. One broad classification of such manually employed dental instruments includes double ended instruments. Typically, these double ended instruments have a pencil-like handle with a specialized tool mounted to each end of the handle. This broad category of dental instruments is commonly referred to as curettes. For the purposes of the present invention, the category of curettes includes carvers and filling instruments, as well as specialized scrapers or scoops, commonly referred to as cleoids and discoids.
The conventional double ended dental instrument includes a handle having two tapered ends. Inserted into each of these ends are tips. The tips are designed for specific and specialized tasks. The user, typically the dentist or hygienist, may require differing sizes, diameters, and shapes of tips to perform any particular dental procedure. The need for efficient, precise and well-designed dental instruments has resulted in many patents issued for improvements on the basic and conventional design.
U.S. Pat. No. 4,552,531 to Martin shows an example of a conventional dental instrument with a simple improvement in its tip system. The conventional, rod-like handle of Martin '531 includes a cross hatched knurling. The handle also includes sockets at each end for receiving tips. The tips of Martin '531 are replaceable with a novel "snap-fit" mechanism. As disclosed by Martin '531, the tips are preferably made from conventional materials such as stainless steel or chrome plated brass, and still fit into a handle that presents problems for the user. When a user must hold a metal instrument of a small diameter for an extended period of time, the user will likely begin to show some sign of chronic fatigue in the finger muscles.
Improvements relating to the handle of the dental instrument often are directed toward improving the grip. The conventional metal handle, even when engraved with cross hatching or knurling, is difficult to hold onto when wet or when the user is wearing protective gloves, as is normally the case. U.S. Pat. No. 5,501,597 to Wilson discloses a dental instrument with gripping handles formed from an elastomeric material. The Wilson '597 gripping handle material is applied onto the ends of a "typical" dental instrument having an elongate shaft and knurled surfaces. Wilson '597 only teaches the utilization of an elastomeric gripping handle on a typical dental instrument, and more specifically only teaches the addition of the gripping handles to the end portions of the handle.
Typical dental instruments are manufactured by milling or grinding a block or rod of material into a desired shape, typically a pencil-like shape. Injection molding is an alternative to conventional milling and grinding for the manufacturing of the dental instrument's handle. Injection molding is discussed in U.S. Pat. No. 5,682,665 to Svanberg. Svanberg '665 discloses an injection mold process for manufacturing a dental curette. The Svanberg '665 method employs a metal injection molding process that results in an instrument of a unitary construction. Additionally, Svanberg '665 briefly suggests that ceramic or thermoplastic powders could be used in injection molding. Svanberg '665 also teaches color coding the instrument for identification of the curette blade's particular configuration. A problem with the Svanberg '665 method is that it can only produce a dental instrument composed from a single, homogenous material. No single material can provide the required properties for the tips, handles and grips that are needed in a precision dental instrument. A need exists for an injection molded dental instrument formed from more than a single material.
A two material, metal and plastic dental instrument is found in U.S. Pat. No. 4,759,713 to Heiss et al. Heiss et al. '713 discloses a disposable dental tool manufactured by over-molding or insert-molding a handle about a wire. While suggesting plastic materials, the Heiss et al. '713 instrument is designed for one-time, single patient, disposable use. Heiss et al. '713 teaches that these plastic handle materials will degrade when sterilized by conventional heat sterilization techniques.
As the U.S. Pat. No. 5,090,907 to Hewitt et al. teaches, dental instruments are typically held by the hand with the tip of the middle finger pressed upon the tapered portion of the handle. Hewitt et al. '907 discloses a dental curette having a finger pad mounted to the tapered tip of the curette's shaft. To be effective, Hewitt et al. '907 teaches that a finger gripping aid must extend to the tapered portion of the handle. Hewitt et al. '907 adds a bulbous finger pad to a conventional dental instrument to achieve this added finger gripping ability. A dental instrument is needed that reduces fatigue and the occurrence of chronic tendon, joint and muscle injury commonly associated with the long term occupational use of conventional dental instruments.
In an alternative, Hewitt et al. '907 suggests that a sleeve of resilient material could be utilized. The resilient material is taught by Hewitt et al. '907 to be silicone rubber or plastic. Hewitt et al. '907 is somewhat similar to Wilson '597 in design and importantly only teaches the retrofit of conventional metal dental instruments with their finger grips.
Additionally, although Heiss et al. '713 does suggest radiation and ethylene oxide sterilization as an alternative sterilization to make the instrument reusable, these sterilization techniques are neither widely available nor accepted, primarily due to environmental health concerns. Therefore, a molded dental instrument is needed that can be reused after sterilization with conventional heat sterilizing techniques.
U.S. Design Pat. No. 33,517 to McKeown, shows a dental instrument handle with apparent ergonomic features, but also includes rows of bumps on what appears to be the grip portion of the handle. The ornamental bumps of McKeown '517 also appear to have a functional purpose, potentially improving a user's frictional grip upon the instrument. However, the bumps on the handle of the McKeown '517 instrument are only present at the middle portion of the handle. Additionally, for sterilization purposes, Hewitt et al. '907 teaches that the finger pad is removable. An ergonomic dental instrument handle is needed that includes true finger gripping features, rather than the ornamental features of McKeown '517, but with non-removable finger grips permanently incorporated into a sterilizable dental instrument.
Seemingly ornamental features would be advantageous in the tracking and personalization of a particular instrument if such features would be resistant to autoclaving and chemclaving environments. A personalized and trackable dental curette is needed that is easily distinguishable and trackable for use by or as belonging to specific doctors or technicians, and for specific purposes or procedures.